Impact drill



R. E. SNYDER IMPACT DRILL Filed Sept. l, 1949 April 14, 1953 IN V EN TOR. @naar I wmf/2 After/2g avi Patented Apr. 14, A 1953 IMPACT DRILL Robert E. Snyder, Pasadena, Calif., assignor to Snyder Oil Tool Corporation, a corporation of California Application September 1, 1949, Serial No. 113,615

My invention relates generally to earth boring drills, and more particularly to a rotary impact drill having hammer means reciprocably mounted on the drill shank and adapted to impact on a suitable anvil member whereby to drive a rotating bit periodically against the formation.

In my Patent No. 2,425,012, issued August 5, 1947, entitled Impact Drill, I have shown and described an earth boring drill of novel design lwherein the drilling uid or mud acts to retard a portion of the drill so that relative rotation is provided between this portion of the -drill and the shank thereof. The relative rotation is then used to operate suitable means, such as cam means, to cause a hammer to impact against the bit or a member connected thereon so as to drive the bit against the formation being drilled. By the use of my improved drill, greatly increased drilling speeds have been obtained, with a consequent lowering of drilling costs.

In my previously mentioned patent, the relative rotation was secured by a body member having outwardly projecting blades or vanes designed to engage the drilling fluid or mud but not the Wall of thebore, the movement of the vanes through the mud causing a drag upon the body member thatV created the desired difference in rotational speeds. In certain other patent applications, hereinafter mentioned, I have shown various means of using this dierence in rotational speeds to operate the impact or hammer means.l In this present application, I disclose an impact .drill having a body member designed to engage the wall of the hole and thus provide a difference in rotational speeds between the body member and the drill shank, this diiference being used to operate any suitable impact-producing mechanism.

During drilling operations, one of the greatest dangers encountered is that of jamming or hanging up the drill within the earth bore. Should this occur, the operation may become a complete loss, or a highly expensive fishing or whipstocking job may be necessary. Likewise, it can be appreciated that the hole drilled should, insofar as Dossible, be straight and of relatively uniform diameter, since either a crooked or an undercut hole increases the danger of hanging up the drill. For these reasons, prior impact drills having wall engaging means that projected into or mutilated the wall of the hole have been unsuccessful in drilling operations, and their use has been abandoned. f

It is a major object of this invention to provide a rotary impact drill having no projections or outwardly extending members that will hang up on the wall of the bore or cause an undercutting thereof.

9 Claims. (Cl. Z55-27) A further object of my invention is to provide an impact drill having rotatable wall engaging means adapted to slide over the surface of the wall and spread or trowel the drilling mud thereagainst whereby to smooth and strengthen the wall.

Another object of my invention is to provide a drill of these general characteristics that does not lrely upon the Wall strength of the earth formaof my improved drill as it `appears in an earth bore;

Fig. 2 is a cross-sectional View taken on the line 2--2 of Fig. 1;

Fig. 3 is a cross-sectional View taken on the line 3 3 of Fig. 1; and

Fig. l is a cross-sectional view taken on the line 4 4 of Fig. 1.

Referring now to the drawings and particularly to Fig. 1 thereof, the numeral I0 indicates generally a drill shank which is lowered within an earth bore I I and rotated by means of a conventional drill stem to drive a drill bit I2. As is customary in such drills, the shank IQ has an axial passage I3 therethrough for carrying drilling fluid or mud to the bit l2. To facilitate connection of the bit I2, the lower end of the shank I0 is provided with an outwardly extending iiange or operating head I4 having suitable means such as a threaded box or pin (not shown) for engaging and locking the bit thereon.

The bit I2 carries a plurality of blades I5 for abrading and cutting the formation, and has ports I6 through which thedrilling iiuid is ejected adjacent the blades. The drilling uid then carries therock, sand, and other detritus cut by the blades i5 upwardly around the shank I0 to the surface where the detritus is removed, and the cleaned fluid returned to the drill. Suitable equipment for maintaining circulation of the fluid and for rotating the shank l0 is provided, usually at the upper end of the hole, and it will be understood that this construction and operation is conventional, and I do not claim these elements in and of themselves as my invention.

To create impacts onthe bit I2, I mount on the shank I cam means which are operable upon relative rotation between a body member 25 and the shank. The outer surface of the body member or slip tube 25 is formed to engage and slide against the wall of the bore II and thereby be retarded with respect to the shank I, as will hereinafter be more fully described. In my previously mentioned patent and applications, I have disclosed various methods for transforming the relative rotation between a retarded member and a drill shank into reciprocatory motion of a hammer body. In the preferred form of the device shown herein, I use one of the simplest of these methods in which the body member or slip tube 25 is connected to an upper cam or hammer I8 while a lower cam or anvil I'I is rigidly mounted on the shank III. The adjacent end faces of the cams I'I and I8 are formed with cooperating lobes or crests thereon which are normally frictionally engaged, the upper cam I8 being driven by the lower or driving cam I'i through the rotation of the shank I5. Upon relative rotation between the slip tube 25 and the shank It, the upper cam I8 will be raised with respect to the lower cam I? and then dropped downwardly to impact against the latter and create a shock that is transmitted through the shank III to the drill bit I2. Other cam and impact means can, of course, be used, and I wish it to be understood that the method shown herein of transforming the relative rotation of the slip tube 25 into reciprocatory motion of the hammer body or upper cam I8 is by way of illustration only.

The retarder means or slip tube 25 is preferably of cylindrical shape having a relatively smooth outer surface adapted to slide in frictional engagement with a portion of the wall of the bore II, and is rotatably mounted on the shank I above the upper cam I8. Suitable keying means connect the lowerl end of the slip tube 25 with the upper cam I3 so that they are fixed to rotate together, while axial movement of the cam is permitted. The slip tube 25 is of extended length and is supported at its upper end by bearing means on the shank I5. An annular cap 26 is provided on the upper end of the slip tube 25 to support a sleeve bearing El by means of an inner web or spider 28 which partially closes the end of the slip tube. The bearing 2? is loosely fitted on the sha-nk I0, and as is best seen in Fig. 2, f

the spider' 28 is formed with a series of ports E5 therein so as to allow free passage of the drilling fluid from the slip tube 25. Above and below the bearing 21 are spaced collars Se and 3i, respectively, which are secured on the shank I0 to hold .Y

the slip tube 25 axially in position, and normally the entire weight of the slip tube will be supported by the shank IIE through the lower collar 3I. The clearance in the bearing 2 and the spacing of the collars 35 and SI are such that the slip tube 25 is only loosely held with respect to the shank IU and is free to incline within and to be thrown centrifugally outwardly against the bore II, as will hereinafter be explained.

The body of the slip tube 25 in the preferred form is a tubular member 45 with an outer diameter slightly smaller than that of the bit I2. This construction forms an annular space 4l of substantial width between the member 4G and the shank Ill, to allow free upward ow of the drilling fluid. Since there is a small clearance between the member 45 and the wall of the bore i i, some of the fluid can pass up around the outside slip tube 25, but most of the circulation will be through the tube in the annular space 4I.

Under some conditions where the bit I2 wears rapidly with a consequent loss of gauge of the well bore II, the body 40 may be split longitudinally into sections and normally collapsed inwardly for ease of moving it axially in the bore when running into or pulling out of the hole. Upon rotation, the body 40 may be forced outwardly into engagement with the surface of the bore by spring means, hydraulic means, or other conventional mechanisms, and it is to be understood that the body 4t is not restricted to the simple design shown herein.

To connect the slip tube 25 with the upper cam I8, a plurality of radially disposed and parallel splines or keys 42 form an extension of reduced diameter below the member 49, and have their upper ends tapered outwardly at 43 to join thereon. The lower ends of the keys 42 are engaged with a cooperating set of keyways 44 formed in the upper cam I8 to provide rotational coupling between the slip tube 25 and the cam, and allow a limited axial movement therebetween. Since the slip tube 25 is suspended at its upper end by the bearing 2l, it does not rest on the cam I8 and in no way interferes with the reciprocation of the latter, the keyways 44 being of such length as to provide substantial clearance with the ends of the keys 43.

Between the tapered portions 43 of the keys 42 are a plurality of apertures 45 to allow passage of the drilling fluid into the annular space 4I within the slip tube 25. The rise of the cam I8 is not sufficient to close the apertures 45 which remain open at all times. As is best seen in Figs. 2 and 3, the apertures 45 and the ports 29 provide a free path for the iiow oi drilling fluid through the slip tube 25, and as shown by the iiow arrows in Fig. l, the ow is straight with a minimum of turbulence. For this reason, the rate of circulation of the drilling iiuid can be varied over a wide range without exceeding normal and practical pumping pressures.

Above the upper cam I8 and surrounding the shank I0 in the preferred form is a resilient means such as a coil spring 50 which is constrained between the cam and a c-ollar 5I amxed to the shank and abutting the upper end of the spring. The spring 50 is compressed as the cam I8 overrides the cam I'I to change the quality of the impact upon the downward strike of the cam I8. For a complete discussion of the effect of different arrangements of resilient members, reference is made to my co-pending application Ser. No. 764,975, filed July 31, 1947, now abandoned, wherein the factors affecting the choice of a resilient member are considered. As was previously mentioned, the weight of the upper cam I8 will cause it to impact upon reciprocation without the use of the spring 50, and the preferred form of the device represents but one of the many ways in which such an apparatus may be constructed.

Basically, the slip tube 25 is retarded by frictional engagement with the walls of the bore I I. When the frictional forces become sufficiently large, the slip tube 25 will lag with respect to the rotation of the shank Il), and the cam I8 is caused to override the cam I'I. The amount of retarding friction needed to overcome the frictional engagement between cams I 'I and I8 is dependent upon the pressure between the faces of the cams, and this pressure may, of course, be varied, as for example, by changing the weight of the hammer member or the character of the resilient springs.

Y As the slip tube 25 is rotated within the well bore II, it is loosely centered on the shank III by the upper bearing 21 and the engagement of the keys 42 and keyways 44 at its lower end. The amount of clearance provided between the shank Ill and the bearing 21 is greater than between the tubular shell 40 and the walls of the bore II. This construction allows the slip tube 25 to move into frictional engagement with a portion of the wall of the bore II without causing any binding of the bearing 21 on the shank I0, and in effect, the slip tube floats on the shank.

The slightest unbalanced force will tend to incline or cant the slip tube 25 into engagement with the wall of the bore II, and as indicated in Figs. l and 2, the top of the slip tube 25 has been moved into engagement with the wall at the left hand side of the drawing. Under actual drilling conditions, the drill is suspended on a relatively flexible column of drill pipe of great length, to which large torque is being applied, and there will always be some slight irregular force sufficient to cause an inclining of the slip tube 25.

' 'I'he area of surface contact between the slip tube 25 and the wall of the bore II is substantial and there is frictional or resisting force set up at the common boundary tending to resist rotation of the slip tube 25. It can be appreciated that the wall of the bore II is comprised of sections of the various strata encountered and presents a generally irregular surface. Drilling fluids ordinarily used with rotary drilling equipment are viscous muds having semi-plastic qualities, and they carry a relatively large pro portionate content of suspended particles, inasmuch as one of their principal functions is to carry away the cuttings from the drill blade. Because of its plastic nature, the drilling fluid tends to form a coating or wall cake upon the interior surface of the bore II as the slip tube 25 is rotated. The manner in which the mud is pushed outwardly into contact with the surface of the bore I I can be best described as a troweling action which in itself causes a frictional resistance; The lubricant factor of the mud will be diminished by the abrasive solids, rock chips, etc., contained therein, and these particles will grind between the slip tube 25 and the bore II and develop substantial frictional engagement therewith.

' It will be remembered that the slip tube 25 is Iloosely supported on the shank I and is inclined within the well bore II so that it rotates eccentrically about the axis of the shank. A centrifugal 25 outwardly against the wall of the bore I I, and since the bearing 21 is suioiently spaced from the shank I0, there is no binding force developed to prevent relative rotation between the slip tube and the shank. The troweling action is greatly increased by the eccentric rotation of the slip tube 25 and the total friction is likewise much larger.

Since the frictional forces are developed largely by the rotation of the slip tube 25, they will normally be insuflicient to stop its rotation, and though the slip tube will lag considerably behind the shank I0, it will nevertheless rotate at a, substantial speed. This normal rotation of the slip tube 25 prevents the drill from hanging up in the bore II, and a major difficulty found in prior impact drills having wall-engaging means which were not designed to rotate is thereby overcome.

A further disadvantage found in prior drills force is thereby created to urge the slip tube having wall engaging means is that they depend upon the strength of the wall surface for retarding, and consequently when relatively soft strata are encountered, the drill pulls the wall in on itself and causes a jam, or in any event undercuts a substantial portion of the bore wall. As used herein, I define the term undercutting to mean the removal of the wall material, the dislodging of rock or boulders, or any other action which tends to mutilate the wall of bore II. It can be appreciated that the smooth outer surface of the slip tube 25 has little tendency to undercut the wall of the bore I I, and, in fact, the troweling action actually strengthens the wall surface.

As the retardation of the drill is created by Vsliding frictional engagement, and not by fluid drag as it is with some of the bladed structures disclosed in my previously'mentioned patent, it can be understood that under certain drilling conditions, my presently disclosed drill may be highly advantageous.

I have described herein a very simple form of my device, one which is rugged and constructed for long life under ldifhcult drilling conditions, and it is apparent that many modifications may be made in the structure. As for example, the variety of cam means shown and described in my co-pending application Serial No. 734,989, filed March 15, 194'1, now abandoned, are well adapted for use on the present device when it is desired to produce a particular type of impact such as a heavy impact followed by a light one, or the reverse sequence. Nor is the construction limited to the elements shown, as any of the improvements disclosed in my :zo-pending application Serial No. 153,941, led June 11, 1947, now abandoned, such as replaceable wearing elements, or improved fastening means, are equally adaptable to the present form of the device. These and other changes can be made by those skilled in the art, an-d it is to be understood that I do not limit myself to the details of construction or design herein shown, other than as defined in the appended claims.

Iclaim:

1. A rotary impact drill for earth boring which includes: a shank adapted to have a bit attached thereon and to be rotated in an earth bore; retarder means loosely mounted on said shank so as to rotate eccentrically relative thereto and for sliding frictional engagement with the wall of said bore without undercutting said wall; and impact means reciprcoably mounted on said shank and responsive to relative rotation between said shank and sai-d retarder means to produce periodic impacts on said shank. Y 2. A rotary impact drill for earth boring which includes: a shank adapted to have a bit attached thereon and to be rotated in an earth bore having drilling fluid therein; impact means reciprocably mounted on said shank; a tubular member of extensive area eccentrically rotatably mounted on said shank and adapted for sliding frictional engagement with the wall of said bore to thereby decrease the rotary speed of said member; and means responsive t0 re1- ative rotation between said shank and said member for operating said impact means.

3. A rotary impact drill for earth boring which includes: a shank adapted to have a bit attached thereon and to be rotated in an earth bore having drilling fluid therein; a driving cam mounted on said shank and rotatable therewith; a driven cam mounted on said shank and adapted to be rotated by rotation of said driving cam, one of said cams being reciprocable on said shank; and a tubular member rotatable eccentrically about said shank and connected to said driven cam for rotation therewith, said member being engageable with the bore wall and being formed with a relatively smooth outer surface to slide in. frictional engagement with a portion of the wall of said bore and trowel said drilling iuid thereagainst, the area of contact being sufhcient to decrease the rotary speed of said member and establish relative rotation between said cams, thereby causing said reciprocable cam to reciprocate and produce an impact on said shank.

4. A rotary impact drill for earth boring which includes: a sank adapted to have a bit attached thereon and to be rotated in an earth bore having drilling mud therein; impact means recip rocably mounted on said shank; a tubular member rotatably mounted on said shank and spaced therefrom to form a passage for drilling mud therebetween, said member being mounted and adapted to slide in frictional engagement with a portion of the wall of said bore and troweling drilling mud thereagainst sufciently to decrease the rotary speed of said member without undercutting said bore wall, said tubular member being mounted sufliciently loosely on said shank so that it can bear against said bore when said shank is in operating position; and cam means responsive to relative rotation between said shank and said tubular member for operating said impact means.

5. In a rotary impact drill including a shank adapted to have a bit attached thereon, impact means associated with said shank; a tubular member loosely and rotatably mounted on said shank and operatively associated with said impact means to operate the same upon `differential rotation between said member and said shank, said member having an outer diameter slightly less than that of said bit and a relatively smooth outer surface capable of engaging and sliding in frictional contact with a bore Wall upon rotation of said shank in said bore and being of sufcient length to thereby decrease the rotary speed of 'said member and thereby operate said impact means by reason of the relative rotation between said shank and said member.

6. In a rotary impact drill including a shank adapted to have a bit attached thereon, impact means associated with said shank, and cam means to operate said impact means: a tubular member connected to said cam means and eccentrically and rotatably mounted on said shank, being spaced therefrom to form a passage for drilling fluid therebetween, said member being of substantial length and having an outer diameter slightly less than that of said bit and a relatively smooth outer surface capable of engaging and sliding in frictional contact with a bore wall without undercutting sai-d wall, upon rotation of said shank in said bore, to thereby decrease the rotary speed of said member and operate said impact means in response to the relative rotation between said shank and said member.

7. In a rotary impact drill including a shank adapted to have a bit attached thereon, impact means associated with said shank, and means to operate said .impact means: a tubular member rotatably mounted on said shank and operatively associated with said impact operating means, said member being of substantial length and having an outer diameter less than that of said bit and an outer surface formed to permit said member to frictionally engage and slide upon and against a portion of a bore wall without undercutting said wall when said shank is rotated in said bore, to thereby decrease the rotary speed of said member and operate said impact means in response to the relative rotation between said shank and said member; and bearing means loosely supporting said member on said shank and having suicient clearance with the latter for eccentric rotation of said member in said bore without binding on said shank.

8. In a rotary impact Adrill including a shank adapted to have a bit attached thereon, impact means reciprocably mounted on said shank, and overriding cams mounted on said shank to operate said impact means, one of which cams is rotatable with said shank; a tubular member loosely and rotatably mounted on said shank and spaced therefrom to form a passage for drilling fluid therebetween, said member being keyed to the other of said cams whereby rotation of said shank causes rotation of said -member because of the frictional engagement between said cams, said member being of substantial length and having an outer diameter slightly less than that of said bit and a relatively smooth outer surface capable of sliding along and against a portion of a bore wall without undercutting said wall, and troweling said drilling iiuid thereagainst when said shank is rotated in said bore, to decrease the rotary speed of said member with respect to said shank and cause said cams to override.

9. A rotary impact drill for earth boring which includes: a shank adapted to have a bit attached thereon and to be rotated in an earth bore having drilling mud therein; a driving cam mounted on said shank and rotatable therewith; a driven cam rotatable with respect to said shank but frictionally urged to rotate therewith by said driving cam, one of said cams being reciprocable on said shank and adapted to impact on the other cam when relative rotation therebetween occurs to produce an impact on said shank; a tubular member engaged with said -driven cam and rotatably mounted on said shank, being spaced therefrom to form a passage for drilling mud therebetween, said member being of substantial length and having an outer diameter slightly less than that of said bit and a relatively smooth outer surface capable of sliding along and against a portion of a bore wall without undercutting said wall, and troweling said drilling mud thereagainst when said shank is rotated in said bore, to decrease the rotary speed of said member and thereby retard said driven cam; and bearing means loosely supporting said member on said shank and having suiiicient clearance with the latter for eccentric rotation of said member in said bore without binding on said shank.

ROBERT E. SNYDE'R.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,745,351 Bishop Feb. 4, 1930 1,821,212 Granger Sept. 1, 1931 2,228,482 Prebensen Jan. 14, 1941 2,287,157 Wolff June 23, 1942 2,425,012 Snyder Aug. 5, 1947 

